4.1 District Heating Storage
The energy content of a typical district heating storage: 70 kWh/m3 [8]
Investment: 1192 DKK/m3 [8]
Sifre input [8]:
Type: DH storage
ADAPT: Investment cost: 0.017 MDKK/MWh
ADAPT: O&M cost: 0 DKK/MW/y
ADAPT: Life time: 30 y [G]
Maintenance: 0 Weeks/y
Outage Probability: 0%
Operating Cost:
Charge rate: 200 MW [G]
Discharge rate: 200 MW [G]
Start-up capacity : 10 MWh (to avoid very high DH price in the first hour)
Charge efficiency: 100%
Discharge efficiency: 100%
Loss: 0.0001 %/h 4.2 Oxygen storage
It has been very difficult to find investment costs for pressurerized oxygen storage vessels. The best available data, is has been able to find under the given timeframe is data for compressed air storage. It is assumed, that a storage vessel for compressed air also can be used for Oxygen.
The found vessel is a 3105 m3 vessel operating at 103 bar. This is a fine match as many ASU unit deliver the oxygen at 90 bar (has to be checked, if the energy consumption for the used ASU concept includes compression to 90 bar).
The purchase cost for this vessel is estimated to M16 USD and the installed cost to M49 USD [12]. As this storage “vessel” consists of 34 storage vessels, it is assumed, that the pricing for other sizes are linear.
To calculate the amount of oxygen stored in such a vessel, The Ideal Gas Law is used:
PV=nRT, R= 0.082, P: pressure in atm, V: volume in liter, n: number of mole gas, T: temperature in Kelvin.
n = PV/RT
n = 88.8*3105000/0.082*310 = 10,846,735 mole O2
To be able to deliver gas to the pressurised gasifier, it is assumed, that the lowest pressure in the O2 storage is 30 bar. The content of the storage is then:
n = 29.6*3105000/0.082*310 = 3,615,578 mole O2
The active storage capacity is therefore: 7.23 mill mole O2 that equals 231.4 t O2
With the arbitrary LHV on O2 set to 0.001 MJ/kg, the “energy” content of the storage is: 0.0643 MWh
The specific cost of the storage then becomes: 274 MDKK/0.0643 MWh = 4261 MDKK/MWh Sifre input (option 1):
Type: O2 storage
ADAPT: Investment cost: 4261 MDKK/MWh [12]
ADAPT: O&M cost: 0 DKK/MW/y [G]
ADAPT: Life time: 30 y [G]
Maintenance: 0 Weeks/y
Outage Probability: 0%
Operating Cost:
Charge rate: 1 MW
Discharge rate: 1 MW
Charge efficiency: 100%
Discharge efficiency: 100%
Loss: 0 %/h
If liquid oxygen is produced for storage (ASU-51) the storage is a totally different kind. The storage then should not be able to manage high pressure but instead very low temperature, as Oxygen is liquid below -183°C. The density is much higher than compressed Oxygen. The stor-age tank in option 1 can contain 231 t O2 while the same storage volume can contain 3,543 ton liquid oxygen. It has not been possible to find investment cost for liquid O2 storage in this pro-jects timeframe, but it is recommended to get such budget data from tank suppliers. For now the tank cost for compressed oxygen/air storage is used. But as the density is 15 times higher the cost per MWH is estimated to be 15 times lower. Normally there is a need for heat supply for evaporation before use in gasification but it is assumed that mixing with the main stream oxygen from Electrolysis at 850-1000°C will supply enough heat.
Sifre input (option 2):
Type: O2 storage
ADAPT: Investment cost: 284 MDKK/MWh [12]
ADAPT: O&M cost: 0 DKK/MW/y [G]
ADAPT: Life time: 30 y [G]
Maintenance: 0 Weeks/y
Outage Probability: 0%
Operating Cost:
Charge rate: 1 MW
Discharge rate: 1 MW
Charge efficiency: 100%
Discharge efficiency: 100%
Loss: 0 %/h
4.3 SynGas storage
It has been very difficult to find investment costs for pressurerized gas storage vessels. The best available data, is has been able to find under the given timeframe is data for compressed air storage. It is assumed, that a storage vessel for compressed air also can be used for com-pressed SynGas. The found vessel is a 3105 m3 vessel operating at 103 bar. The SynGas is pro-duced at 25 bar. In the Methanol Synthesis the syngas is compressed up to 90 bar. It is as-sumed, that the storage at this point in the process and therefore a storage at 90 bar will re-quire no extra compression of the syngas at inlet to storage. A minor compression at the outlet of the storage is necessary to 90 bar again, if the storage level is low. The energy consumption for this compression is not jet included in the simulation. The temperature just before the Methanol Synthesis is approximately 60°C [3]
The purchase cost for this vessel is estimated to M16 USD and the installed cost to M49 USD [12]. As this storage “vessel” consists of 34 storage vessels, it is assumed, that the pricing for other sizes are linear.
To calculate the amount of SynGas stored in such a vessel, The Ideal Gas Law is used:
P*V=n*R*T, R= 0.082, P: pressure in atm, V: volume in liter, n: number of mole gas, T: temper-ature in Kelvin.
n = P*V/R*T
n = 88.8*3105000/0.082*333 = 10,097,561 mole SynGas
To reduce the power consumption for compression at the outlet it is assumed, that the storage operates between 90 bar and 30 bar. The content of the storage is then:
n = 29.6*3105000/0.082*333 = 3,365,854 mole SynGas
The active storage capacity is therefore: 6.73 mill mole SynGas that equals 75.7 t SynGas (11.25 g/Mole [3])
With LHV on Syngas just before Methanol Synthesis at MJ/mole, the energy content of the storage is: 457.7 MWh.
The specific cost of the storage then becomes: 274 MDKK/457.7 MWh = 0.60 MDKK/MWh Sifre input:
Type: SynGas storage
ADAPT: Investment cost: 0.6 MDKK/MWh [12]
ADAPT: O&M cost: 0 DKK/MW/y [G]
ADAPT: Life time: 30 y [G]
Maintenance: 0 Weeks/y
Outage Probability: 0%
Operating Cost:
Charge rate: 100 MW
Discharge rate: 100 MW
Charge efficiency: 100%
Discharge efficiency: 100%
Loss: 0 %/h